POSsimulator | Python Fiddle

__author__ = 'jsgreenwell'

import POSFunctions #our custom class
from collections import OrderedDict

"""Basic change making program using 100 base (American Currency): will create full knapsack version in
   later example. This example will also be expanded, in steps, until it becomes a simple OO-based
   (ie. we'll add classes) POS system with database tie-in and GUI UI.

This version just adds a very basic commandline UI that will eventually be replaced by database and
   POS (tk) system. It also imports a custom class for handling POS Functions.
"""

StoreInventory = {
    132: {"name": "banana", "price": .56, "qoh": 10},
    333: {"name": "fish", "price": 4.56, "qoh": 3},
    378: {"name": "frozen dinner", "price": 7.59, "qoh": 20},
    388: {"name": "beef", "price": 4.98, "qoh": 8},
    908: {"name": "peas", "price": 2.98, "qoh": 11}
} #not the best method for this; Only for testing before database creation

def display_inventory():
    """
    Displays the inventory in a semi-formatted fashion. Print will be replaced by GTK display then
    a database call will be added. Using a simple for range of 0-4 is a good method of displaying
    matching keys and values when the values are equal sized keys
    :return: void
    """

print "Inventory Display\n  ID |      NAME    | PRICE | QOH "
    for id in OrderedDict(sorted(StoreInventory.items(), key=lambda t: t[0])):
        print '{0:^5}|{1:^14}|{2:^7}| {3}'.format(id, StoreInventory[id]["name"],
                                            StoreInventory[id]["price"], StoreInventory[id]["qoh"])
        # 0:^5 = first passed arg:(center) padding of 5 spaces

def main():
    """
    Main here includes a lot of the actual processing, this is both just due to us testing and because that's just how
    it is sometimes. Create working code first, optimize later - means that sometimes programmers will not have time
    to separate the logic the way they might eventually want to. This can also be on purpose if the program is small
    or only performs one or two functions.
    """

pos = POSFunctions.RegisterFunctions(123432) #Just sending a random number as sale rep ID for now
    item_id = 0
    purchased_qty = 0

display_inventory()

while item_id != 999:
        # TODO: Add Error checking and input valuidation (ie. ID exists, qty is available)
        item_id = int(raw_input("Enter the Item ID Number (999 to exit): "))
        if item_id != 999:
            purchased_qty = int(raw_input("Enter the Quantity Purchased: "))
            pos.addpurchase(item_id, StoreInventory[item_id]["name"], purchased_qty, StoreInventory[item_id]["price"])
            StoreInventory[item_id]["qoh"] -= purchased_qty

print "Your Total Price is ${0:.2f}".format(pos.calctotalsale())
    """
    There is an error that sometimes occurs here (you might see it) where the change due is sometimes +/- .01 off
    between the total here and the calculated change later. This is due to a floating point rounding error and it will
    be covered later (when numpy is introduced). For now just be aware of it.
    """

while pos.total > pos.payment:
        pos.addpayment(float(raw_input("Please enter a payment amount: "))) #Should error check then pass

print pos.getchange()
    
main()

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